I'm not even entirely sure where the point here is. That Capitalism doesn't have this inherent flaw, people do, ergo the solution is better people, capitalism is fine? Complete of course with some good old founding fathers choice cherry picking.
If that's the case, the biggest flaws right off the bat here is A. Idealism vs pragmatism and B. Wholly ignoring external issues. The intersection of Government and the private sector is an ever shifting set of compromises. Because the reality is people can't and don't make the best, most rational choices as voters or consumers. "People", with no central point of planning or authority, are a mob. Undefined, unorganized, unchecked, unqualified in most aspects given a choice to decide in any particular case.
Mob rule is what you get when people decide, wholly based on popular choice, what the laws, statues, rules, and regulations are. That has proven to be a horrible, ineffective, and inefficient way to Govern a Nation. That's why the U.S. has NEVER had that. Not even as colonists. Which is baffling that your father would cite that as some golden era of rugged individualism.
I'm sure he's heard of the Whiskey Rebellion, where George Washington used the people, organized as a militia under central authority, to put down an uprising over alcohol taxes. That is one of many, many examples that conflicts with the narrative that the founders were proto-libertarians. I'd also like to add that, in all those declarations of natural rights, all that talk of liberty, it never applied to people who were black, and hardly to women. This ought to be a clue further still that taking quotes out of context can divorce them from the speaker's intentions.
Getting back on track, the critcism's leveled at Capitalism because of inherent greed are done so precisely because flawed, imperfect humans utilize it and that produces the end result. Given the choice of maximizing profit in rapid succession over issues of ethics, stability, or external considerations, it's shown over and over and over where Capitalistic intentions lead to disasters. It's sociopathic and predatory in the same ways unchecked Government can be despotic and heavy handed. People can hold government accountable annually in the polls; you have no voice in a corporation unless you are a shareholder, and even then, you better control a big piece of the pie or share the interests of the majority other shareholders to hold sway in big decisions.
That's what I've got for now; there's more to say here, a lot more, but hopefully others say it.